Differential haptic guidance for personal navigation

An adaptive system for measuring the angular position of a rotating shaft, the system comprising:

• a field source configured to generate a measurable field;
• a sensor configured to measure the generated field;
• and
• a target that is configured to modify the generated field as measured by the sensor to have a shape (a) with at least one measurable feature for a zero angular reference, and (b) that varies throughout one or more angles such that a rotational position of the shaft is determined according to a selected angular interval;
• the adaptive system having a first mode of operation for self-calibrating the adaptive system to identify minimum and maximum values of the generated field measured by the sensor;
• and
• the adaptive system having a second mode of operation using the minimum and maximum values to determine a corresponding angular position of the shaft relative to a preselected position;
• wherein the system is configured to output information of the identified values to a control device to control operation of the shaft.